package crypto.aes;


import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Base64;


public class AES256 {

  public static byte[] encrypt(String content, String password) {
    try {
      //"AES"：请求的密钥算法的标准名称
      KeyGenerator kgen = KeyGenerator.getInstance("AES");
      //256：密钥生成参数；securerandom：密钥生成器的随机源
      SecureRandom securerandom = new SecureRandom(tohash256Deal(password));
      kgen.init(256, securerandom);
      //生成秘密（对称）密钥
      SecretKey secretKey = kgen.generateKey();
      //返回基本编码格式的密钥
      byte[] enCodeFormat = secretKey.getEncoded();
      //根据给定的字节数组构造一个密钥。enCodeFormat：密钥内容；"AES"：与给定的密钥内容相关联的密钥算法的名称
      SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
      //将提供程序添加到下一个可用位置
      Security.addProvider(new BouncyCastleProvider());
      //创建一个实现指定转换的 Cipher对象，该转换由指定的提供程序提供。
      //"AES/ECB/PKCS7Padding"：转换的名称；"BC"：提供程序的名称
      Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");

      cipher.init(Cipher.ENCRYPT_MODE, key);
      byte[] cryptograph = cipher.doFinal(content.getBytes("utf-8"));
      return Base64.encode(cryptograph);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return null;
  }

  public static String decrypt(byte[] cryptograph, String password) {
    try {
      KeyGenerator kgen = KeyGenerator.getInstance("AES");
      SecureRandom securerandom = new SecureRandom(tohash256Deal(password));
      kgen.init(256, securerandom);
      SecretKey secretKey = kgen.generateKey();
      byte[] enCodeFormat = secretKey.getEncoded();
      SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
      Security.addProvider(new BouncyCastleProvider());
      Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");

      cipher.init(Cipher.DECRYPT_MODE, key);
      byte[] content = cipher.doFinal(Base64.decode(cryptograph));
      return new String(content);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return null;
  }

  private static String parseByte2HexStr(byte buf[]) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < buf.length; i++) {
      String hex = Integer.toHexString(buf[i] & 0xFF);
      if (hex.length() == 1) {
        hex = '0' + hex;
      }
      sb.append(hex.toUpperCase());
    }
    return sb.toString();
  }

	/*private static byte[] parseHexStr2Byte(String hexStr) {
		if (hexStr.length() < 1)
			return null;
		byte[] result = new byte[hexStr.length()/2];
		for (int i = 0;i< hexStr.length()/2; i++) {
			int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);
			int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);
			result[i] = (byte) (high * 16 + low);
		}
		return result;
	}*/

  private static byte[] tohash256Deal(String datastr) {
    try {
      MessageDigest digester = MessageDigest.getInstance("SHA-256");
      digester.update(datastr.getBytes());
      byte[] hex = digester.digest();
      return hex;
    } catch (NoSuchAlgorithmException e) {
      throw new RuntimeException(e.getMessage());
    }
  }

  public static void main(String[] args) {

    String content = "0f607264fc6318a92b9e13c65db7cd3c";
    String password = "zsyy";
    System.out.println("明文：" + content);
    System.out.println("key：" + password);

    byte[] encryptResult = AES256.encrypt(content, password);
    System.out.println("密文：" + AES256.parseByte2HexStr(encryptResult));

    String decryptResult = AES256.decrypt(encryptResult, password);
    System.out.println("解密：" + decryptResult);
  }

}
